Technical Field
The present invention generally relates to medical devices, and in particular medical catheters with optical capabilities and/or steering capabilities.
Background of Related Art
An endoscope is an illuminated usually fiber-optic flexible or rigid tubular instrument for providing direct visualization to the interior of a hollow organ or part (as the bladder or esophagus) for diagnostic or therapeutic purposes that typically has one or more channels to enable passage of instruments (as forceps or scissors). The scope is inserted through a natural opening, such as the mouth during a bronchoscopy or the rectum for a sigmoidoscopy.
Because current endoscopes have outer shaft diameters of approximately 5 mm or greater, they typically can only be used in relatively large body lumens. As a consequence, they can only provide direct visualization to the large lumen and the entrance to the small lumens that branch off. In order to examine a small lumen further, i.e., beyond the entrance, a catheter has to be inserted through the working channel of the endoscope and then passed down into the small lumen. Visualization is then done through radiographical means.
A variety of attempts have been made to provide catheters capable of navigating into small lumens to provide direct visualization and treatment. For example, U.S. Pat. No. 7,922,650 to McWeeney et al. discloses a direct visualization system that includes a reusable optical assembly and a disposable co-linear multi-lumen, steerable catheter that can be tracked over a guidewire. The catheter, which has a 10 French (3.3 mm) outer diameter, has one working channel, two irrigation channels, and a dedicated optical assembly lumen. The optical assembly, which has a diameter of approximately 0.77 mm is made of a fiber optic bundle surrounded by lights. Because the optical assembly is free of the catheter and has a small crossing profile it is able to enter normal bile and pancreatic ducts, which have diameters as small as 2 to 3 mm. However, the catheter itself, with a 3.3 mm crossing profile, is still restricted access. As a result, visualization which starts out moderate at best due to use of fiber optics is further impaired by any stone debris or sludge that cannot be properly flushed from a distance. In addition, the optical assembly is fragile and must be handled with care.
U.S. Pat. No. 7,922,654 to Boutillette et al. discloses a small diameter steerable imaging catheter with at least one steering cable extending along the catheter tube to control movement of the distal end and a fiber optic cable extending along the catheter tube. The catheter tube is constructed to have greater flexibility near its distal end portion while having greater stiffness in the remainder of the tube. It also discloses that this may be accomplished by varying durometer ratings of the materials used to form the catheter tube. It further discloses that this construction concentrates the flexing at the distal end portion, rather than throughout the entire catheter tube, to thereby reduce undue twisting of the catheter tube along its entire length, and further to permit better control of the movement of the distal end portion. In order to provide a smaller diameter steerable imaging catheter, the '654 patent provides a shaft with fewer independent channels (lumens) than the '650 patent which relies solely on shaft design and steering wires, not a guidewire, for navigation. The lack of independent channels results in the sharing of channels that are present. For instance, irrigation or flushing of the fiber optic may be interrupted if a cutting wire is needed for cutting out undesirable material. Interruption in flow will result in impaired visualization due to sludge or debris that cannot be properly flushed from in front of the fiber optic during the procedure. Also, the '654 patent uses fiber optic technology in the design due to its small delivery diameter. Like the '650 patent, this creates a fragile device with poor image quality.
Both of the above patents disclose co-linear multi-lumen tubes with at least one of the lumens dedicated to a fiber optic for viewing. In addition, both require the use of push/pull or steering wires, which are placed circumferentially around the catheter adding to the overall size.
There exists a need for smaller diameter devices with imaging capability. The need further exists for such smaller diameter devices that are highly navigable with an imaging technology that presents high resolution, color images to aid in the diagnosis and treatment of a patient. It would further be beneficial if such devices could be designed with deflection without increasing their size to thereby maintain their low profile. It would also be beneficial if such devices could enable flushing of the imaging devices to aid visualization.